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Mantero A.,National Institute of Nuclear Physics, Italy | Ben Abdelouahed H.,Center National des science et Technologies Nucleaires | Champion C.,University of Lorraine | El Bitar Z.,CNRS Hubert Curien Multi-disciplinary Institute | And 7 more authors.
X-Ray Spectrometry | Year: 2011

Geant4 is a general purpose and open source C + + Monte Carlo simulation toolkit, widely used in the scientific community. It is able to simulate physical interactions of particles through matter. According to the user's needs, models for the simulation of electromagnetic (EM) interactions are provided in two Geant4 subpackages, the 'standard' EM subpackage, well suited for a wide range of applications and the 'low-energy' EM subpackage, able to reach the electronVolt regime. Particle-induced X-ray emission (PIXE) is a well known and a very useful technique for quantitative elemental analysis in environmental, archaeological, biological, medical and space applications. An atomic de-excitation module is part of the Geant4 'low-energy' EM subpackage since 1999 and has been validated in recent years. PIXE simulation has been included in this subpackage in 2001 and new ionisation cross-sectional models following the ECPSSR theory have been added for the PIXE simulation in 2008. In 2010, these models have been further extended to higher energies. In this work, we present new results on the verification of these models and an overview of the new interface to PIXE modelling prepared for the recent public release of the Geant4 toolkit (December 2010) allowing a unified usage of the Geant4 de-excitation module by both 'standard' and 'low-energy' subpackages. © 2011 John Wiley & Sons, Ltd.

Ivantchenko A.V.,University of Bordeaux 1 | Ivantchenko A.V.,Geant4 Associates International Ltd | Ivanchenko V.N.,Geant4 Associates International Ltd | Ivanchenko V.N.,CERN | And 2 more authors.
International Journal of Radiation Biology | Year: 2012

Purpose: To test and to develop Geant4 (Geometry And Tracking version 4) Monte Carlo hadronic models with focus on applications in a space radiation environment. Materials and methods: The Monte Carlo simulations have been performed using the Geant4 toolkit. Binary (BIC), its extension for incident light ions (BIC-ion) and Bertini (BERT) cascades were used as main Monte Carlo generators. For comparisons purposes, some other models were tested too. The hadronic testing suite has been used as a primary tool for model development and validation against experimental data. Results: The Geant4 pre-compound (PRECO) and de-excitation (DEE) models were revised and improved. Proton, neutron, pion, and ion nuclear interactions were simulated with the recent version of Geant4 9.4 and were compared with experimental data from thin and thick target experiments. Conclusions: The Geant4 toolkit offers a large set of models allowing effective simulation of interactions of particles with matter. We have tested different Monte Carlo generators with our hadronic testing suite and accordingly we can propose an optimal configuration of Geant4 models for the simulation of the space radiation environment. © 2012 Informa UK, Ltd.

PubMed | Geant4 Associates International Ltd, University of Wollongong and Bordeaux Gradignan Center of Nuclear Studies
Type: Journal Article | Journal: Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) | Year: 2016

Nanoparticles (NPs) have been shown to enhance X-ray radiotherapy and proton therapy of cancer. The effectiveness of radiation damage is enhanced in the presence of high atomic number (high-Z) NPs due to increased production of low energy, higher linear energy transfer (LET) secondary electrons when NPs are selectively internalized by tumour cells. This work quantifies the local dose enhancement produced by the high-Z ceramic oxide NPs Ta

Allison J.,University of Manchester | Allison J.,GEANT4 Associates International Ltd. | Garnier L.,Laboratoire Of Laccelerateur Lineaire | Kimura A.,Ashikaga Institute of Technology | Perl J.,SLAC
International Journal of Modeling, Simulation, and Scientific Computing | Year: 2013

From the beginning, the GEANT4 Visualization System was designed to support several simultaneous graphics systems written to common abstract interfaces. Today, it has matured into a powerful diagnostic and presentational tool. It comes with a library of models that may be added to the current scene and which include the representation of the GEANT4 geometry hierarchy, simulated trajectories and user-written hits and digitizations. The workhorse is the OpenGL suite of drivers for X, Xm, Qt, and Win32. There is an Open Inventor driver. Scenes can be exported in special graphics formats for offline viewing in the DAWN, VRML, HepRApp and gMocren browsers. PostScript can be generated through OpenGL, Open Inventor, DAWN and HepRApp. GEANT4's own tracking algorithms are used by the Ray Tracer. Not all drivers support all features but all drivers bring added functionality of some sort. This paper describes the interfaces and details the individual drivers. © 2013 World Scientific Publishing Company.

Karamitros M.,Bordeaux Gradignan Center of Nuclear Studies | Karamitros M.,French National Center for Scientific Research | Luan S.,University of New Mexico | Bernal M.A.,University of Campinas | And 16 more authors.
Journal of Computational Physics | Year: 2014

Context Under irradiation, a biological system undergoes a cascade of chemical reactions that can lead to an alteration of its normal operation. There are different types of radiation and many competing reactions. As a result the kinetics of chemical species is extremely complex. The simulation becomes then a powerful tool which, by describing the basic principles of chemical reactions, can reveal the dynamics of the macroscopic system.To understand the dynamics of biological systems under radiation, since the 80s there have been on-going efforts carried out by several research groups to establish a mechanistic model that consists in describing all the physical, chemical and biological phenomena following the irradiation of single cells. This approach is generally divided into a succession of stages that follow each other in time: (1) the physical stage, where the ionizing particles interact directly with the biological material; (2) the physico-chemical stage, where the targeted molecules release their energy by dissociating, creating new chemical species; (3) the chemical stage, where the new chemical species interact with each other or with the biomolecules; (4) the biological stage, where the repairing mechanisms of the cell come into play. This article focuses on the modeling of the chemical stage.Method This article presents a general method of speeding-up chemical reaction simulations in fluids based on the Smoluchowski equation and Monte-Carlo methods, where all molecules are explicitly simulated and the solvent is treated as a continuum. The model describes diffusion-controlled reactions. This method has been implemented in Geant4-DNA. The keys to the new algorithm include: (1) the combination of a method to compute time steps dynamically with a Brownian bridge process to account for chemical reactions, which avoids costly fixed time step simulations; (2) a k-d tree data structure for quickly locating, for a given molecule, its closest reactants. The performance advantage is presented in terms of complexity, and the accuracy of the new algorithm is demonstrated by simulating radiation chemistry in the context of the Geant4-DNA project.Application The time-dependent radiolytic yields of the main chemical species formed after irradiation are computed for incident protons at different energies (from 50 MeV to 500 keV). Both the time-evolution and energy dependency of the yields are discussed. The evolution, at one microsecond, of the yields of hydroxyls and solvated electrons with respect to the linear energy transfer is compared to theoretical and experimental data. According to our results, at high linear energy transfer, modeling radiation chemistry in the trading compartment representation might be adopted. © 2014 Elsevier Inc.

Allison J.,Geant4 Associates International Ltd | Allison J.,University of Manchester | Apostolakis J.,CERN | Bagulya A.,RAS Lebedev Physical Institute | And 17 more authors.
Journal of Physics: Conference Series | Year: 2012

An overview of the current status of electromagnetic physics (EM) of the Geant4 toolkit is presented. Recent improvements are focused on the performance of large scale production for LHC and on the precision of simulation results over a wide energy range. Significant efforts have been made to improve the accuracy without compromising of CPU speed for EM particle transport. New biasing options have been introduced, which are applicable to any EM process. These include algorithms to enhance and suppress processes, force interactions or splitting of secondary particles. It is shown that the performance of the EM sub-package is improved. We will report extensions of the testing suite allowing high statistics validation of EM physics. It includes validation of multiple scattering, bremsstrahlung and other models. Cross checks between standard and low-energy EM models have been performed using evaluated data libraries and reference benchmark results.

Ivanchenko V.N.,CERN | Ivanchenko V.N.,Russian Academy of Sciences | Apostolakis J.,CERN | Bagulya A.,RAS Lebedev Physical Institute | And 12 more authors.
Journal of Physics: Conference Series | Year: 2014

In this work we present recent progress in Geant4 electromagnetic physics modelling, with an emphasis on the new refinements for the processes of multiple and single scattering, ionisation, high energy muon interactions, and gamma induced processes. The future LHC upgrade to 13 TeV will bring new requirements regarding the quality of electromagnetic physics simulation: energy, particle multiplicity, and statistics will be increased. The evolution of CPU performance and developments for Geant4 multi-threading connected with Geant4 electromagnetic physics sub-packages will also be discussed. © Published under licence by IOP Publishing Ltd.

Apostolakis J.,CERN | Bagulya A.,RAS Lebedev Physical Institute | Elles S.,LAPP | Ivanchenko V.N.,CERN | And 4 more authors.
Journal of Physics: Conference Series | Year: 2010

The software tools developed for the validation and verification of the standard electromagnetic physics package of Geant4 are described. The validation is being performed versus experimental data and in regression to a previous version of Geant4. Examples of validation results are presented. © 2010 IOP Publishing Ltd.

Schalicke A.,German Electron Synchrotron | Bagulya A.,RAS Lebedev Physical Institute | Dale O.,CERN | Dale O.,University of Bergen | And 10 more authors.
Journal of Physics: Conference Series | Year: 2011

An overview of the electromagnetic physics (EM) models available in the Geant4 toolkit is presented. Recent improvements are focused on the performance of detector simulation results from large MC production exercises at the LHC. Significant efforts were spent for high statistics validation of EM physics. The work on consolidation of Geant4 EM physics was achieved providing common interfaces for EM standard (HEP oriented) and EM low-energy models (other application domains). It allows the combination of ultra-relativistic, relativistic and low-energy models for any Geant4 EM processes. With such a combination both precision and CPU performance are achieved for the simulation of EM interactions in a wide energy range. Due to this migration of EM low-energy models to the common interface additional capabilities become available. Selected validation results are presented in this contribution.

Ivanchenko V.N.,CERN | Ivanchenko V.N.,Moscow State University | Kadri O.,NCNST | Maire M.,CEA DAM Ile-de-France | Urban L.,Geant4 Associates International Ltd
Journal of Physics: Conference Series | Year: 2010

Recent progress in development of single and multiple scattering models within the Geant4 toolkit is presented. Different options available to users are discussed. The comparisons with the data are shown. The trade of precision versus CPU performance is discussed with the focus on LHC detectors simulation. © 2010 IOP Publishing Ltd.

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